MX2012004423A - Producing edible residues from ethanol production. - Google Patents

Abstract

Edible residues of ethanol production, e.g., distillers grains and solubles, are produced that are low in, or substantially free from, antibiotic residues. Antibiotics or bacteria present in edible residues resulting from ethanol production are inactivated by irradiating the edible residues.

Description

PRODUCTION OF RESIDUES COM ESTIZES AT PARTI PRODUCTION OF ETAN OL Related requests This application claims the priority to the provisional serial US request no. 61/251, 610, filed on October 14, 2009.

Technical field This invention relates to producing edible residues from the production of ethanol, for example, grains of distillers and residues from the production of cellulosic ethanol.

Background The manufacture of plants exists for the production of ethanol from grains, for example, corn and sugars. The manufacture of ethanol is discussed in many sources, for example, in The Alcohol Textbook, 4th ed. , ed. , K.A. Jacques, et al. , Nottingham University Press, 2003. Distillery grains (also referred to distillers grains and solubles (DGS) or dry distillers grains (DDGS)) are a by-product of ethanol production. Grains of distillers are a valuable by-product, since they are a main source of low-cost livestock feed. However, concerns have recently arisen due to the presence of antibiotics in the distillery grains. Antibiotics in distillery grains are usually present as a result of the use of antibiotics in the ethanol manufacturing process. Antibiotics, such as penicillin and virginiamycin, are used to control bacteria that compete with yeast during fermentation, turning sugar into lactic acid instead of ethanol. If restrictions on the sale or use of distillers grains are imposed due to concerns about the content of antibiotics, this will further harm the profit margins of ethanol producers, as well as deprive farmers of a good source of livestock feed.

The US patent application no. 200601 27999, "Process for producing ethanol from corn dry m i l l i ng" (Process for the production of ethanol from dry corn milling), and U.S. patent application no. 20030077771, "Process for producing ethanol", are each incorporated by reference in their entirety In addition, U.S. Patent No. 7,351, 559"Process for producing ethanol", US Pat. No. 7,074,603, "Process for producing ethanol from corn dry milling" and the US patent No. 6,509, 180, "Process for producing ethanol" (Process for producing ethanol). each is incorporated by reference herein in its entirety.

Short description In general, this invention relates to edible residues a from the production of ethanol, and to methods for producing edible residues that are low in antibiotic content or, in preferred embodiments, substantially free of antibiotics. By "low in antibiotic content" or "substantially free of antibiotics", we mean that the edible residue contains little or no active antibiotic, for example, less than 100 ppm; the edible residue may contain inactivated antibiotics, as will be described herein.

The edible residue can be, for example, dried distillers' grains (DDG), in the case of corn ethanol production, or a mixture of lignin, unfermented sugars (for example, xylose, arabinose), minerals (e.g. clay, silica, silicates), and in some cases undigested cellulose.

In some implementations, the edible residue contains less than 50 ppm by weight of active antibiotic, eg, less than 25 ppm, less than 10 ppm, or even less than 1 ppm.

In one aspect, the invention features a method comprising irradiating edible residues that have been produced as a by-product of an ethanol manufacturing process.

Some implementations include one or more of the following characteristics. The edible residues comprise distillers grains and soluble ones, for example, from a corn ethanol process. Alternatively, the edible residues may comprise lignin, xylose and minerals, and in some cases undigested cellulose, for example, when the ethanol manufacturing process uses a cellulosic feed and / or a lignocellulosic feed.

In some cases, edible residues contain an antibiotic, and irradiation is performed under conditions that are selected to inactivate or destroy the antibiotic, for example, by changing the molecular structure of the antibiotic. In such cases, after irradiation the edible residues may contain less than 100 ppm, such as less than 50, 25, 10 or 1 ppm, by weight of active antibiotic, or may be substantially free of active antibiotic. In some implementations, before the irradiation the edible residues contain from about 500 ppm up to about 1 0,000 ppm by weight of active antibiotics.

In other cases, the ethanol manufacturing process can be conducted without the addition of antibiotics. In such cases, before the irradiation the edible residues may contain bacteria and the irradiation is carried out under conditions that destroy bacteria.

In some implementations, the irradiation is delivered at a dose of more than about 0.5 Mrad and / or less than about 5 Mrad, for example, at a dose of about 1 to about 3 Mrad.

If the edible residues are distiller's grains and soluble, the distillers 'grains and solubles can be dried, producing dry and soluble distillers' grains (DDGS). The drying can be carried out before, during or after the irradiation.

All publications, patent applications, patents and other references mentioned herein or attached herein are incorporated by reference in their entirety for everything they contain.

Description of the drawings FIG. 1 is a schematic diagram illustrating a process for making ethanol and distillers grains.

Detailed description With reference to FIG. 1, a plant for making ethanol can include, for example, one or more units of operation (10) for physically receiving and treating a feed, which in a typical plant based on diet (eg, M oz og ra no) g ene ra l lt includes grain receiving equipment and hammer mill. If the feed to be used is a cellulosic or lignoceluosic material other than grains, the operating units 10 can be configured to reduce the size of the feed in a manner that exposes internal fibers of the feed, for example, as described in FIG. US patent no. 7,470,463, the disclosure of which is incorporated herein by reference.

In some cases, for example, if the feed includes a material that is difficult to treat by fermentation, for example, crop residues or other lignocellulosic feeds, the plant may include an optional operation unit configured to treat the feed to reduce its recalcitrance. . In some implementations, the recalcitrance is reduced by at least 5%, or at least 1 0, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90 or 95%. . In some cases, recalcitrance is substantially eliminated completely. The treatment processes used by the recalcitrant reducing operation unit may include one or more of irradiation, sonication, oxidation, pyrolysis and vapor explosion. The treatment methods can be used in combinations of two, three, four or even all these technologies (in any order). The units of operation that pretreat feeds to reduce recalcitrance are described in WO 2008/031 86, the complete description of which is incorporated herein by reference.

The feed can then be processed in a series of cooking devices (12), as is well known, subjected to liquefaction (14), and cooled (16) to a temperature suitable for contact with microorganisms, such as yeasts. The cooled stream then flows to a bioprocessing system (18), where it is bio-processed, for example, fermented, to produce a mixture of crude ethanol which flows into a holding tank (20).

The bio-processing system may in some cases use antibiotics to prevent the excessive generation of lactic acid by bacteria in the mixture. For example, the antibiotic can be added in a concentration from about 500 ppm to about 10,000 ppm by weight of the feed.

Alternatively, the use of antibiotics can be avoided, for example, by cleaning the feed and processing equipment, running the process at low pH levels, and maintaining high performance during soaking, maceration and fermentation. The additives Non-antibiotics can also be used, for example, the hopper extract sold by BetaTec Hop Products under the trade name lsoStabM R. If these alternatives are used, it is desirable to sterilize the edible residues of the process, to ensure their safety.

Water or other solvent, and other non-ethanol components, are extracted from the crude ethanol mixture using an extraction column (22), and the ethanol is then distilled using a distillation unit (24), for example, a rectifier. Finally, the ethanol can be dried using a molecular sieve (26), denatured if necessary and removed to a desired shipping method.

Another stream comes from the bottom of the extraction col- umn (22) and is passed through a centrifuge (28). A liquid fraction, or "thin vinasse (countercurrent)" is then returned to the process, usually before the cooking devices (1 2). The solids ("wet cake") are subjected to further processing, including drying, in an evaporator / dryer operation unit (30), resulting in the production of an edible waste, eg, distillers grains and dry solubles (DDGS). ) if the food was corn.

The edible residue is then irradiated, using an irradiation unit (32). The irradiation serves both to inactivate any antibiotic present in the edible residue from the fermentation process, for example, by changing the molecular structure of the antibiotic, and by sterilizing the edible residue, killing any undesirable bacteria or other microorganism present in the residue. edible.

The irradiation can be carried out using any suitable device. If the edible residue is in the form of a thin section, e.g., small pellets, electron beam irradiation may be preferred to provide high performance. If deeper penetration is required, for example, if the edible residue is in the form of a thick cake, gamma radiation can be used.

The radiation can be delivered in any dose that is sufficient to inactivate the antibiotic and / or destroy undesirable bacteria and microorganisms, without detrimentally affecting the availability of nutrients from the edible residue. For example, the dose may be from about 05 Mrad to about 5 Mrad, for example, about 1 Mrad to about 3 Mrad.

The drying of the edible residue can be done before (as shown), during or after irradiation, or it can be omitted if desired.

In general, all the processing equipment used in the process described above is normally used in existing ethanol processing plants, with the exception of the optional reductive reducing operation unit and the device used to irradiate the edible residue.

In some cases, the feed may be a cellulose or lignocellulosic material that has been physically treated and optionally pre-treated at a remote location and then shipped to the plant, for example, by train, truck, boat (for example, barge or supertanker), or air. In such cases, the material can be shipped in a densified state for volume efficiency. For example, the feed can be physically treated, for example, using the size reduction techniques described below, or at a bulk density of less than about 0.35 g / cm 3, and then densified to have a bulk density of at least approximately 0.5 g / cm3. In some implementations, the densified material may have a bulk density of at least 0.6, 0.7, 0.8 or 0.85 g / cm3. The fibrous materials can be densified using any suitable process, for example, as described in WO 2008/0731 86.

The feeding can be in some cases fibrous in nature. Fiber sources include cellulosic fiber sources, including paper and paper products (eg, poly-coated paper and kraft paper), and lingocellulosic fiber sources, including wood and related materials, eg, particle board. Other suitable sources of fiber include sources of natural fibers, for example, grass, rice husks, bagasse, cotton, jute, hemp, flax, bamboo, sisal, abaca, straw, corn cobs, rice husks, coconut fiber; fiber sources high in a-cellulose content, for example, cotton. Fiber sources can be obtained from virgin cut fabric materials, for example, remnants, post consumer waste, for example, rags. When paper products are used as sources of fiber, they can be virgin materials, For example, virgin cut materials, or they can be post consumer waste. In addition to virgin, post-consumer, industrial raw materials (eg, offal) and processing waste (eg, paper processing effluent) can also be used as fiber sources. In addition, the fiber source can be obtained or derived from human waste (eg wastewater), animal or vegetable. Additional fiber sources have been described in US Pat. Nos. 6,448,307, 6,258,876, 6,207,729, 5,973,035 and 5, 952, 1 05.

The sugars released during bioprocessing can be converted into a variety of products, such as alcohols or organic acids. The product obtained depends on the microorganism used and the conditions under which bio-processing occurs. These steps can be performed using the existing equipment of the grain-based ethanol manufacturing facility, with little or no modification. A stream of xylose (C5) can be produced during bio-processing, if hemi-cellulose is present in the feed, and thus in some cases provision is made to remove this current after the extraction column.

The microorganism used in bioprocessing can be a natural microorganism or a designed microorganism. For example, the microorganism can be a bacterium, for example, a cellulolytic bacterium, a fungus, for example, a yeast, a plant or a protista, for example, an algae, a protozoan or a protista as a fungus, for example, a slime mold. When organisms are compatible, mixtures of organisms can be used. The microorganism can be an aerobic or anaerobic. The microorganism can be a homofermentative microorganism (produces a single or substantially a single final product). The microorganism can be a homozygogenic microorganism, a homolactic microorganism, a propionic acid bacterium, a butyric acid bacterium, a succinic acid bacterium or a 3-hydroxypropionic acid bacterium. The microorganism can be of a genus selected from the group Clostridium, Lactobacillus, Moorella, Thermoanaerobacter, Proprionibacterium, Propionispera, Anaerobiospirillum and Bacteriodes. In specific cases, the microorganism can be Clostridum formicoaceticum, Clostridum butyricum, Moorella thermoacetica, Thermoanaerobacter kivui, Lactobacillus delbrukii, Propionibacterium acidipropionici, Propionispera arboris, Anaerobiospirillum succincproducens, Bacteriodes amylophilus or Bacteriodes ruminicola. For example, the microorganism can be a recombinant microorganism designed to produce a desired product, such as a recombinant Escherichia coli transformed with one or more genes capable of encoding proteins that direct the production of the desired product (see, for example, the patent). US No. 6,852,517, issued February 8, 2005).

Bacteria that can ferment biomass to ethanol and other products include, for example, Zymomonas mobilis and Clostridium thermocellum (Philippidis, 1996, supra). Leschine et al. (International Journal of Systematic and Evolutionary Microbiology 2002, 52, 1155-1160) isolated a cellulolytic bacteria, mesophilic, anaerobic, from forest soil, Clostridium phytofermentans sp. Nov., which converts cellulose to ethanol.

Bio-processing, for example, fermentation, from biomass to ethanol and other products can be performed using certain types of thermophilic or genetically engineered microorganisms, such as Thermoanaerobacter, including T. mathranii and yeast species such as Pichia species. An example of a strain of T. mathranii is A3M4 described in Sonne-Hansen et al. (Applied Microbiology and Biotechnology 1993, 38, 537-541) or Ahring et al. (Arch. Microbiol. 1997, 168, 114-119).

To aid in the breakdown of materials including cellulose (treated by any method described herein or even untreated), one or more enzymes, for example, a cellulolytic enzyme may be used. In some embodiments, materials that include cellulose are first treated with the enzyme, for example, by combining the material and the enzyme in an aqueous solution. This material can then be combined with any microorganism described herein. In other embodiments, materials that include cellulose, one or more enzymes and the microorganism are combined concurrently, for example, by combining in an aqueous solution.

The carboxylic acid groups in these products generally lower the pH of the fermentation solution, tending to inhibit fermentation with some microorganisms, such as Pichia stipitis. Accordingly, it is in some cases desirable to add a base and / or a buffer, before or during fermentation, to raise the pH of the solution. For example, sodium hydroxide or lime can be added to the fermentation medium to raise the pH of the medium to vary that which is optimal for the microorganism used.

The fermentation is generally conducted in an aqueous growth medium, which may contain a source of nitrogen or other source of nutrients, for example, urea, together with vitamins and minerals and trace metals. It is generally preferable that the growth medium be sterile, or at least have a low microbial load, for example, bacterial count. The sterilization of the growth medium can be achieved in any desired manner. However, in preferred implementations, sterilization is achieved by irradiating the growth medium or individual components of the growth medium prior to mixing. The radiation dosage is generally as low as possible while still obtaining adequate results, in order to minimize the energy consumption and resulting cost. For example, in many cases, the growth medium itself or components of the growth medium can be treated with a radiation dose of less than 5 Mrad, such as less than 4, 3, 2 or 1 Mrad. In specific cases, the growth medium is treated with a dose between approximately 1 and 3 Mrad.

Other modalities A variety of modalities has been described. However, it will be understood that several modifications can be made without departing from the spirit and scope of the description.

For example, although the production of dry and soluble distillers' grains (DDGS) is discussed above, in some cases the final product may instead be wet and soluble distillers grains (WDGS). Although WDGS, with its high moisture content, is generally expensive to transport and subject to spoilage, in some cases it can be used, for example, where livestock feed will be used near the ethanol manufacturing facility. Such applications are described, for example, in U.S. Pat. 6,355,456, the complete description of which is incorporated herein by reference.

Either wet milling or dry milling processes can be used in the methods described herein.

Accordingly, other embodiments are within the scope of the following claims.

Claims (16)

1. CLAIMS 1 . A method comprising: irradiate edible waste that has been produced as a by-product of an ethanol manufacturing process. 2. The method of claim 1, wherein the edible residues comprise distillers grains and solubles. 3. The method of claim 1 or 2, wherein the ethanol manufacturing process is a corn ethanol process. 4. The method of claim 1, wherein the edible residues comprise lignin, xylose and minerals. 5. The method of claim 4, wherein the edible waste further comprises undigested cellulose. 6. The method of claim 1, 4 or 5, wherein the ethanol manufacturing process uses a cellulosic feed and / or a lignocellulosic feed. 7. The method of any of the preceding claims, wherein the edible residues contain an antibiotic, and the irradiation is performed under selected conditions to inactivate or destroy the antibiotic. 8. The method of claim 7, wherein after irradiation, the edible residues contain less than 1 00 ppm, such as less than 50, 25, 10 or 1 ppm, by weight of active antibiotic. 9. The method of claim 8, wherein the edible residues are substantially free of active antibiotic. 10. The method of claim 7, wherein prior to irradiation, the edible residues contained from about 500 ppm to about 10,000 ppm by weight of active antibiotic. eleven . The method of any of claims 1-6, wherein prior to irradiation, the edible residues contain bacteria, and the irradiation is carried out under conditions that destroy the bacteria. 12. The method of claim 1, wherein the ethanol manufacturing process was conducted without the addition of antibiotics. 1 3. The method of claim 2, in distillers and solubles, has been dried, producing dry and soluble distillers grains (DDGS). 14. The method of claim 1, wherein the drying is performed before irradiation. The method of any of the preceding claims, wherein the irradiation is delivered at a dose of more than about 0.5 Mrad. 16. The method of any of the preceding claims, wherein the irradiation is delivered at a dose of less than about 5Mrad. The method of any one of the preceding claims, wherein the irradiation is delivered at a dose from about 1 to about 3 Mrad.